Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-01-31
2003-07-08
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
Reexamination Certificate
active
06590307
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of German patent application DE P 10104419.4 filed Feb. 1, 2001, herein incorporated by reference.
1. Field of the Invention
The invention is relative to a device for the radial attitude control of a rapidly rotating rotor, especially a spinning rotor, supported in a contactless manner.
2. Background of the Invention
Contactless, passive support bearings or contactless, active supports with regulators for attitude stabilization or damping of oscillations are known in a great variety of embodiments.
For example, German Patent Publication DE 33 23 648 A1 shows a magnetic support comprising an actuating mechanism with electromagnetic coils. The magnetic support comprises two bearing parts offset relative to one another along the direction of the axis of rotation of a rotor. Translatory deviations of the instantaneous position of the axis of rotation from an ideal position are to be determined for two directions perpendicular to one another and to the axis of rotation of the rotor and stabilized by the controlling of magnetic forces. In addition, tilting movements of the rotor about axes of rotation parallel to the two directions perpendicular to the axis of rotation are determined and a restoring moment generated about these axes, and switching means are further provided for damping the nutation frequency. The nutation of the rotor is damped thereby by cross-coupling branches. Since all attitudinal deviations are stabilized, there is a constant readjusting in the case of high rotor speeds and the actuating mechanism is highly controlled. This is disadvantageous as concerns the consumption of energy and the load on the control elements and causes limitation phenomena in the control of the actuating mechanism, such as, for example, in the amplifiers. In particular, an elevation of amplitude in the so-called D-component in regulators (for example, in PD controllers or regulators) results at high frequencies and at high speeds and thereby results in high amplitude values of the control voltage. As a consequence, the power requirement of such a control is high. When the rotor speed is accelerated, increased power is required only for a brief time, for example, for fractions of a second as the speed passes through a resonance frequency of the support system. High power is constantly necessary in such attitude controls at the high operating speeds of rapidly rotating rotors, such as, e.g., in the case of spinning rotors.
In order to achieve a certain quietness and to be able to operate with less power, it is known that the rotor can be allowed to rotate not about its geometric axis but rather about its axis through the center of gravity or about the axis of inertia. For example, German Patent Publication DE 26 58 668 A1 discloses a magnetic support for a rotor in which the disturbing influences stemming in particular from imbalances and dependent on the rotor speed are reduced by means of a suppression filter. To this end, the control circuit of the magnetic support comprises a filter device interposed between the sensor device and the control circuit for the signals supplied from the sensor device. The filter device is designed as a suppression device whose frequency is adjusted according to the speed of the rotor. The suppression filter filters out disturbances of the rotor attitude that occur periodically with the rotational frequency and that would bring about a constant readjusting of the rotor into the central attitude. To this end, adding circuits and a negative feedback circuit are used. However, great complexity is necessary for the described circuits, which results in a relative great susceptibility to interference in the entire circuit. Moreover, such filter circuits cause significant phase rotations and/or phase errors that are generally recognized as disadvantageous. These phase rotations or errors can amount to more than 90 degrees and can endanger the stability of the control circuit or else which must themselves be compensated for in an expensive manner. Due to the carried-out adjustment of the effect of the suppression filter to a certain rotational speed of the rotor the desired effect does not occur at rotary frequencies deviating from this adjustment.
German Patent Publication DE 31 20 691 A1 describes a magnetic support in which deviations from the geometry of the rotor are detected by a sensor device and stored in a data storage along with the corresponding particular angular position at the rotary motion of the rotor. The detection takes place in a rotor-specific manner and is carried out before the particular rotor is put in operation. The stored values remain preserved for the entire operating time of the rotor. The disturbance signals generated by the sensor device and those deriving from errors of geometry are superposed and thus compensated by means of a correction signal. Unfortunately, the use of such a device, especially in spinning rotors of a rotor spinning machine, has disadvantages. Spinning rotors are subject to wear that can necessitate the replacement of the particular spinning rotor. If necessary, spinning rotors are also replaced during a batch change as a function of the fibrous material or yarn used. Thus, the replacement of spinning rotors that is unavoidably repeated when using spinning rotors requires significant expense on account of repeated detection operations. Also, a rather large computer capacity must constantly be available in order to store the amounts of data and to continuously process them. Further, imbalances which are not traceable to detectable errors of geometry, such as imbalances due to inhomogeneity of the rotor material or due to trash that can adhere and collect in the area of the rotor groove of spinning rotors, are not compensated in the device described in German Patent Publication DE 31 20 691 A1.
SUMMARY OF THE INVENTION
The present invention seeks to address the problem of improving the attitude control of rotors which are supported in a contactless manner.
The invention addresses this problem by providing a sensor device for the continuous generation of rotor attitude signals and a control device for processing the rotor attitude signals. The control device includes a controller that outputs a rotary-frequency-dependent output resultant signal or correcting variable, generated from the rotor attitude signals, for controlling the actuating device. The resultant signal follows the rotary-frequent waveform of the controller output signal at frequencies below the resonance frequencies of the contactless support, while above these resonance frequencies the resultant signal increasingly follows the rotary-frequent waveform of the controller output signal only in the area of at least one of the two extreme values (i.e., the minimum and maximum values) of the waveform, whereby the amplitude of the resultant signal is distinctly smaller than the amplitude of the rotary-frequency-dependent controller output signal. Further, the resultant signal of the rotary-frequency-dependent oscillation maps superposed oscillations of the controller output signal that are low-frequency in comparison to it in a practically unchanged manner.
Such a control device permits, upon the occurrence of rather high oscillatory frequencies, the lowering of the oscillation amplitudes of the oscillation dependent on the rotary frequency with small phase errors at the same time as regards the relatively low resonance frequencies and therewith permits an advantageous reduction of the power consumption of the attitude control as well as increased quietness of the rotor without customary suppression filters and without the above-mentioned disadvantages of the state of the art. The small phase errors that occur thereby do not endanger the stability of the control and are tolerable. On the other hand, the phase rotation that can be produced by customary deep-pass filters is significantly greater.
The reduction of the amplitude of the rotary-frequency-dependent oscillation of the re
Kennedy Covington Lobdell & Hickman LLP
Mullins Burton S.
W. Schlafhorst AG & Co.
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